The adaptive modulation and coding (AMC) mode refers to a data transmission method that determines the modulation scheme and the coding scheme of different data channels depending on the channel status between cells, that is, a base station BS and a mobile station MS, to improve the usability of all cells.
In the case of recent mobile communication systems such as IEEE 802.16 WirelessMAN (wireless metropolitan area network) based WiBro (Wireless Broadband), in order to improve the data transmission speed, a band AMC scheme that distinguishes a better channel and a worse channel depending on the status of the subchannels, and allocates the subchannels to the mobile stations within a range permitted by the resource, is used. When the mobile station transmits data in a band that is allocated by the band AMC scheme, the data can be transmitted using a band having high-quality subchannels. Therefore, it is possible to transmit data stably against noise and interference from adjacent cells, and to increase the coding rate, which improves the transmission speed.
However, there is a case in which the band that is allocated to the mobile station operating in the band AMC mode should be changed due to the status of the subchannels that varies depending on a time change and mobility of the mobile station. That is, the mobile station reconstructs the band for band AMC by periodically measuring CINR (carrier to interference and noise ratio) to check the channel status of the subchannels, to include subchannels having a good status and exclude the subchannels having a bad status. In this case, the mobile station requests that the base station allocates the new band for the band AMC so as to communicate in the reconstructed band.
In the meantime, according to the method that allocates the band requested by the mobile station operating in the band AMC mode to the mobile station, the mobile station selects the band to be allocated on the basis of the channel status of the subchannels. In this case, the allocation of a logically non-adjacent band may be un-desirably requested. As described above, when the allocation of the logically non-ADJACENT bands is repeated, the overhead of MAP is increased. Accordingly, the base station cannot efficiently allocate the resources, nor can it allocate the resources to the other mobile stations due to the allocated band.